Dogs and Infertility
There are several reasons why a female dog (a.k.a. a bitch) may fail to conceive. The following will be an overview of some of the main causes, as well as why reproduction is unsuccessful in these dogs and possible ways to correct the disorders.
The dog may simply have a delayed pubertal heat. Most female dogs go into heat at around six months in small breed dogs, but the pubertal heat may not be until a female is thirty months old in some giant breeds! However, if the female dog is not showing signs of heat in the allotted time, many factors may be the cause.
First of all, the first heat may have simply been ‘silent’. This means that it did occur, but the female did not show behavioural signs, such as the restlessness that is typical of most females. Some female dogs clean themselves so fastidiously that no vaginal discharge (a sign of heat) is noted. Thus, it is easy to miss this first heat, and the owners may find themselves thinking there is something wrong with their dog. A good way of preventing this dilemma is to do what many breeders do. They take a piece of tissue and place it on the female’s vulva as soon as she wakes up in the morning. The reason behind this is that she is generally not licking herself in her sleep, so if she does have any discharge, owners would be able to detect this as soon as she rises.
Pathology may be the root of the problem, however. For example, some bitches can be ‘intersex’; that is they have characteristics of both male and female animals. For example, a female-looking dog may be discovered to have vestigial testes upon ultrasound! These animals are nearly always infertile, even if the testes are removed. Though rare, intersex conditions have been noted in many species, such as horses, cows, and even human beings.
The bitch’s pituitary gland may also be at fault. The pituitary gland is responsible for regulation of many glands of the body, and thus helps regulate the formation of several sex hormones. If the pituitary did not form completely, it is called hypotrophic. Thus, the body does not get the signals it needs to be reproductively capable. Hormone treatments are available, but do not guarantee fertility.
A female dog may also have physical abnormalities which prevent her from getting pregnant. For example, she can have vaginal anomalies, such as tumours, inflammation, or a persistent hymen. She can also get endometritis, where the innermost layer of her uterus becomes infected with bacteria. Since only one layer is affected, the dog will usually not show clinical signs. However, she can go on to develop metritis, where all three layers of her uterus are now heavily infected with bacteria. This is a systemic disease, affecting her entire body, since the bacteria can now escape into her bloodstream. Thus, she will show signs such as fever, depression, vomiting and diarrhea.
Her uterus may also may be inflamed, irritated or filled with pus, a condition known as pyometra. Pyometra occurs when there is a bacterial infection while a bitch is in diestrus. Diestrus is the period of a female’s estrus cycle when the hormone progesterone is highest. Estrogen is thought to increase the capability of the uterus to fight infection; thus, in diestrus, when estrogens are low, the uterus is at a high risk of bacterial invasion. Pyometra is a veterinary emergency; a dog suspected of having it needs to be seen by a veterinarian immediately. Signs to watch for are a dull, depressed dog, with what is often described as a ‘tomato soup’ discharge; a watery, reddish fluid from her vulva. Bitches can have open or closed pyometras. A closed one is considered the worse scenario, since the bacteria is building up with no outlet. In an open pyometra, the bacteria is escaping to some extent through the vaginal discharge. To diagnose pyometra, an ultrasound can be done, and bloodwork will be conducted. Treatment consists of giving her fluids to rehydrate her, as well as antibiotics to kill the bacteria causing the problem. For the vast majority of cases, E. coli is the culprit. The best treatment of pyometra however, and one often carried out to save the bitch’s life, is a spay or ovariohysterectomy. If the uterus is the problem, removing it solves it completely.
There are also infectious causes of infertility, such as bacteria like Brucella, as well as Herpesvirus. Both these infections can cause female dogs to abort even once they do manage to conceive. Often the embryos are tiny and owners do not notice them being passed; thus they believe their dog never got pregnant in the first place. Tests can be done to determine whether the bitch carries these pathogens before she is mated; in fact, many stud owners have testing in their contracts before they allow their stud to be used, since both these pathogens can be sexually transmitted.
If you suspect your dog is having pregnancy or infertility problems, contact your veterinarian ASAP.